1. Field of the Invention
The present invention relates generally to an internal combustion engine and more particularly to an internal combustion engine having a turbo-charger and an auxiliary turbine which is driven by the exhaust gases flowing from the turbo-charger and integrated with the crankshaft of the engine for increasing the power output thereof.
2. Brief Description of the Prior Art
In a previously proposed arrangement such as schematically illustrated in FIG. 1 of the drawings, an auxiliary turbine 1 has been geared to the crankshaft 2 of an internal combustion engine 3 (or auxiliary equipment such as oil pumps etc.) and fed hot expanding exhaust gases from a turbine 4 of a turbo-charger 5 so as to utilize the surplus energy remaining in the exhaust gases and increase the power output of the engine 3, either by adding directly to the engine output through the crankshaft 2 or by reducing the amount of power that must be supplied by the engine to the various auxiliary units attached to the engine (e.g. air conditioning compressors or the like).
In order to control the operation of this arrangement, it has been necessary to provide a waste gate 6 (see FIG. 2) which controls the supercharging pressure by by-passing some of the exhaust gases normally fed to the turbo-charger turbine 4 around same, to the auxiliary turbine 1 geared to the engine crankshaft 2 (or the like).
However, this arrangement has suffered from the drawback in that, as the back pressure prevailing downstream of the turbo-charger turbine 4 varies with the rotational speed of the auxiliary turbine 1 and the amount of exhaust gas by-passed around the turbo-charger turbine, excessive back pressure tends to occur. This excessive back pressure of course undesirably inhibits optimal engine performance the variation of the back pressure and renders it very difficult to match the operation of the turbo-charger and the auxiliary turbine.